The aims of the research are to investigate (1) the epidemiology of the use of marijuana, other illicit drugs and medically prescribed psychoactive substances in a large and representative national probability longitudinal sample of young men and women aged 19-26 in 1984, and (2) selected behavioral correlates, antecedents and consequences of marijuana use in young adulthood. Funds are requested to include five minutes of drug-related questions in the ongoing Youth Cohort, the national longitudinal survey of young adults (NLS) conducted by Ohio State University since 1979. The data will be collected in the last wave of the six-wave longitudinal survey. The national sample (N=12,133) includes an overrepresentation of blacks (N=2,000), Hispanics (N=1,800) and disadvantaged whites (N=1,940), as well as members of the armed forces (N=1,300). A large number of these youths (N=2,400) are school dropouts. The NLS survey includes very detailed questions about labor force participation, schooling and marital history for every wave; a single marijuana use question in Wave 2; health related questions in the first 4 waves; and alcohol questions in Waves 4-6. The National Longitudinal Survey data tapes are public use tapes and will be available to the research community at large. Three specific activities are outlined in the proposal: (1) epidemiological analyses of the use of illicit and medically prescribed drugs in various sociodemographic segments of the young adult population; (2) identification of the behavioral correlates of marijuana involvement, in terms of participation in the roles of young adulthood, schooling, work, marriage and parenthood; and (3) identification of selected antecedents and consequences of marijuana involvement in young adulthood, with special emphasis on the relationship between schooling and labor force participation over time, by relying on the marijuana use data to be obtained retrospectively for the period 1979-1984. Epidemiological estimates of drug use will be available for groups that are generally poorly represented in representative national samples, in an age span that represents periods of highest drug involvement. Relationships of drug involvement with labor force participation and family roles can be investigated in much greater detail than is possible with other data sets.